In a conventional AMOLED (active-matrix organic light-emitting diode) display, pixel units thereof use TFTs (thin-film transistors) that operate in saturation region to drive light emission of OLEDs (organic light-emitting diodes). Such a conventional AMOLED display may have the following drawbacks:
1. Currents generated by TFTs operating in the saturation region are larger than those generated by TFTs operating in subthreshold region. TFTs that operate in the saturation region cannot meet reduced current requirements for display panels of small size and high resolution.
2. TFTs operating in the saturation region have higher power consumption than those operating in the subthreshold region. The problem of high power consumption may become more severe with development trends of high aspect ratio (i.e., a ratio of an area occupied by the OLEDs with respect to the entire display area of a display panel) and high definition (i.e., number of pixel units per unit display area).
3. Due to the lack of current compensation, when threshold voltage drift or degradation occurs in the TFTs and OLEDs, brightness uniformity of the display panel may be adversely affected.